Climate: Scientists surprised by level of ocean acidification impacts off the West Coast of U.S.

In areas, more than half the sampled sea snail shells showed signs of deterioration

By Summit Voice

FRISCO — Increasing concentration of carbon dioxide in the Pacific Ocean is dissolving the shells of tiny free-swimming snails off the West Coast, researchers said this week, confirming a troubling trend that’s been observed even in remote reaches of the Southern Ocean around Antarctica, where researchers with the British Antarctic Survey documented similar findings.

The estimates that the percentage of pteropods affected in the region has doubled since the pre-industrial era and is on track to triple by 2050, when coastal waters become 70 percent more corrosive than in the pre-industrial era due to human-caused ocean acidification.

The pteropods are part of the aquatic food chain, eaten by pink salmon, mackerel and herring. The scientists said they were surprised to find how widespread the impacts of ocean acidification are at this stage.

“We did not expect to see pteropods being affected to this extent in our coastal region for several decades,” said William Peterson, Ph.D., an oceanographer at NOAA’s Northwest Fisheries Science Center and one of the paper’s co-authors. “This study will help us as we compare these results with future observations to analyze how the chemical and physical processes of ocean acidification are affecting marine organisms.”

“Acidification of our oceans may impact marine ecosystems in a way that threatens the sustainability of the marine resources we depend on,” said Libby Jewett, Director of the NOAA Ocean Acidification Program. “Research on the progression and impacts of ocean acidification is vital to understanding the consequences of our burning of fossil fuels.”

The new research documents the movement of corrosive waters onto the continental shelf from April to September during the upwelling season, when winds bring water rich in carbon dioxide up from depths of about 400-600 feet to the surface and onto the continental shelf.

“Our findings are the first evidence that a large fraction of the West Coast pteropod population is being affected by ocean acidification,” said Nina Bednarsek, Ph.D., of NOAA’s Pacific Marine Environmental Laboratory in Seattle, the lead author of the paper.

“Dissolving coastal pteropod shells point to the need to study how acidification may be affecting the larger marine ecosystem. These nearshore waters provide essential habitat to a great diversity of marine species, including many economically important fish that support coastal economies and provide us with food,” Bednarsek said.

In coastal waters from northern Washington to central California, up to 53 percent of the pteropods sampled had severely dissolved shells. The ocean’s absorption of human-caused carbon dioxide emissions is also increasing the level of corrosive waters near the ocean’s surface where pteropods live.

“We did not expect to see pteropods being affected to this extent in our coastal region for several decades,” said William Peterson, Ph.D., an oceanographer at NOAA’s Northwest Fisheries Science Center and one of the paper’s co-authors. “This study will help us as we compare these results with future observations to analyze how the chemical and physical processes of ocean acidification are affecting marine organisms,” Peterson said.

Richard Feely, senior scientist from NOAA’s Pacific Marine Environmental Lab and co-author of the research article, said that more research is needed to study how corrosive waters may be affecting other species in the ecosystem.

“We do know that organisms like oyster larvae and pteropods are affected by water enriched with CO2,” Feely said. “The impacts on other species, such as other shellfish and larval or juvenile fish that have economic significance, are not yet fully understood.”

“Acidification of our oceans may impact marine ecosystems in a way that threatens the sustainability of the marine resources we depend on,” said Libby Jewett, Director of the NOAA Ocean Acidification Program. “Research on the progression and impacts of ocean acidification is vital to understanding the consequences of our burning of fossil fuels.”

The research drew upon a West Coast survey by the NOAA Ocean Acidification Program in August 2011, that was conducted onboard the R/V Wecoma, owned by the National Science Foundation and operated by Oregon State University.